Top cover installation process for a disc drive

ABSTRACT

A top cover installation station with a feeder assembly and a robotic assembly for installing a top cover with top cover fasteners on a basedeck of a disc drive. The feeder assembly supports top cover wireframe caddies, each caddy containing top covers. A dial assembly transports each caddy into alignment with an elevator assembly that aligns the top cover with an escapement assembly that removes the top cover from the caddy. The robotic assembly has a positioning assembly supporting a pair of Z-axis end effector assemblies, the positioning assembly transporting the pair of effector assemblies to predetermined positions. A first end effector assembly picks and places the top cover adjacent the basedeck and a second end effector assembly grips and secures the top cover onto the basedeck via the top cover fasteners.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/641,694 filed Aug. 18, 2000 now U.S. Pat. No. 6,497,036, which claimspriority to U.S. Provisional Application No. 60/150,139 filed Aug. 20,1999.

FIELD OF THE INVENTION

The present invention relates generally to the field of disc drive datastorage devices, and more particularly, but not by way of limitation, toan automated assembly of a disc drive head-disc assembly which includesan automated top cover installation station for installing top covers ondisc drives.

BACKGROUND

Modern hard disc drives are commonly used in a multitude of computerenvironments ranging from super computers through notebook computers tostore large amounts of data in a form that can be made readily availableto a user. Typically, a disc drive comprises one or more magnetic discsthat are rotated by a spindle motor at a constant high speed. Thesurface of each disc serves as a data recording surface and is dividedinto a series of generally concentric recording tracks radially spacedacross a band between an inner diameter and an outer diameter. The datatracks extend around the disc and data is stored within the tracks onthe disc surface in the form of magnetic flux transitions. The fluxtransitions are induced by an array of transducers otherwise commonlycalled read/write heads. Typically, each data track is divided into anumber of data sectors that store fixed sized data blocks.

Each read/write head includes an interactive element such as a magnetictransducer which senses the magnetic transitions on a selected datatrack to read the data stored on the track. Alternatively, theread/write head transmits an electrical signal that induces magnetictransitions on the selected data track to write data to the track. As isknown in the art, the read/write heads are supported by rotary actuatorarms and are positioned by the actuator arms over a selected data trackto either read or write data. The read/write head includes a sliderassembly having an air-bearing surface that causes the read/write headto fly relative to the disc surface. The air bearing is developed byload forces applied to the read/write head by a load arm interactingwith air currents produced by disc rotation.

Typically, several open-centered discs and spacer rings are alternatelystacked on the hub of a spindle motor, followed by the attachment of aclampring to form a disc pack. The hub, defining the core of the stack,serves to align the discs and spacer rings around a common centerline.Movement of the discs and spacer rings is typically constrained by acompressive load maintained by the clampring. The complementary actuatorarms of an actuator assembly, commonly called an E-block, support theread/write heads to access the surfaces of the stacked discs of the discpack. The read/write heads communicate electronically with a printedcircuit board assembly (PCB) through read/write wires and a flex circuitattached to the E-block. When the E-block is merged with the disc packinto a base deck and a cover is attached to the base deck, a head-discassembly (HDA) is formed. For a general discussion of E-block assemblytechniques, see U.S. Pat. No. 5,404,636 issued to Stefansky et al. andassigned to the assignee of the present invention.

The head-disc assembly (HDA) of a disc drive is typically assembled in aclean room environment. A clean room environment (free of contaminantsof 0.3 micron and larger) is necessary to ensure that the head-discinterface remains unencumbered and damage free. The slightest damage tothe surface of a disc or read/write head can result in a catastrophicfailure of the disc drive. The primary causes of catastrophic failure,particularly read/write head crashes (a non-recoverable, catastrophicfailure of the disc drive), are generally characterized ascontamination, exposure to mechanically induced shock and non-shockinduced damage. The source of non-shock induced damage is typicallytraced to the assembly process, and generally stems from handling damagesustained by the disc drive during the assembly process.

Several factors that bear particularly on the problem of assemblyprocess induced damage are the physical size of the disc drive, thespacing of the components, the recording densities sought to be achievedand the level of precision to be maintained during the assembly process.The high levels of precision required by the assembly process arenecessary to attain the operational tolerances required by the discdrive. The rigorous operational tolerances are in response to marketdemands that have driven the need to decrease the physical size of discdrives while simultaneously increasing disc drive storage capacity andperformance characteristics.

Demands on disc drive mechanical components and assembly procedures havebecome increasingly more critical in order to meet the strenuousrequirements of increased capability and size reduction in the face ofthese new market demands. Part-to-part variations in critical functionalattributes in the magnitude of micro-inches can result in disc drivefailures. Additionally, as disc drive designs continue to require sizereduction, smaller read/write heads, thinner substrates, longer andthinner actuator arms, and thinner gimbal assemblies must continue to beincorporated into the drives. This trend significantly exacerbates theneed to improve assembly processes to protect the read/write heads anddiscs from damage resulting from incidental contact between matingcomponents. The aforementioned factors resultantly increase thedifficulty of assembling disc drives, and as the assembly processbecomes more difficult, the need to invent new tools, methods andcontrol systems to deal with the emerging complexities pose uniqueproblems in need of solutions.

Coupled with the size and performance demands is the further marketdriven requirement for ever increasing fault-free performance. Theprogression of continually thinner disc thickness and tighter discspacing, together with increasing track density and increasing numbersof discs in the disc pack, has resulted in a demand for tools, methodsand control systems of ever increasing sophistication. A result has beena decreasing number of assembly tasks involving direct operatorintervention. Many of the tasks involved in modem methods are beyond thecapability of operators to reliably and repeatedly perform, furtherdriving the need for automated equipment and tooling.

In addition to the difficulties faced in assembling modern disc drivesof high capacity and complex, physical product performance requirementshave dictated the need to develop new process technologies to ensurecompliance with operating specifications. The primary factors drivingmore stringent demands on the mechanical components and the assemblyprocess are the continually increasing areal densities and data transferrates of the disc drives.

The continuing trend in the disc drive industry is to develop productswith ever increasing areal densities, decreasing access times andincreasing rotational speeds. The combination of these factors placesgreater demands on the ability of modern servo systems to control theposition of read/write heads relative to data tracks. The ability toassemble HDAs nominally free from the effects caused by unequal loadforces on the read/write heads, disc pack imbalance or one of thecomponents of runout, velocity and acceleration (commonly referred to asRVA) poses a significant challenge as track densities increase. Thecomponents of RVA are disc runout (a measure of the motion of the discalong the longitudinal axis of the motor as it rotates); velocity (ameasure of variations in linear speed of the disc pack across thesurface of the disc); and acceleration (a measure of the relativeflatness of the discs in the disc pack). By design, a disc drivetypically has a discrete threshold level of resistance to withstandrotationally induced noise and instability, below which the servo systemis not impaired. Also, a fixed range of load forces must be maintainedon the read/write head to ensure proper fly height for data exchange.The operating performance of the disc drive servo system is affected bymechanical factors beyond the effects of mechanically induced read/writehead oscillation from disc surface anomalies. Errors are traceable todisc pack imbalance and RVA noise sources. Even with improved approachesto the generation of position error signals in the disc drive servosystem, the ability of the system to deal with such issues is finite.The limits of the servo system capability to reliably control theposition of the read/write head relative to the data track must not beconsumed by the noise present in the HDA resulting from the assemblyprocess. Consumption of the available margin by the assembly processleaves no margin in the system to accommodate changes in the disc driveattributes over the life of the product. An inability to accommodatechanges in the disc drive attributes leads to field failures and anoverall loss in product reliability, a detrimental impact to productmarket position.

Taken in combination the above discussed factors—the tasks involved inassembling a modern disc drive exceeds the capability of manualassemblers; the susceptibility of the disc drive to damage during theassembly process; the level of precision assembly required by increasingareal densities; and the need to minimize adverse effects ofmechanically induced noise on the disc drive servo system—haveculminated to render prior disc drive assembly method archaic. Thus, ingeneral, there is a need for an improved approach to disc driveassembling technology to minimize the potential of damage duringassembly, to produce product that is design compliant and reliable, andto minimize mechanically induced system noise. More particularly, thereis a need for a top cover installation station for installation of a topcover on a disc drive.

SUMMARY OF THE INVENTION

The present invention provides a top cover installation station with afeeder assembly and a robotic assembly for installing a top cover onto abasedeck of a disc drive by top cover fasteners. The feeder assemblysupports several top cover wireframe caddies containing covers, and anescapement assembly for removing the top covers from the caddie. Theescapement assembly includes a linear positioning assembly that supportsand transports a rotary actuator that has a locating pin for registeringthe top cover to the rotary actuator prior to removal of the top coverfrom the top cover wirefitame caddy, and the rotary actuator rotates thetop cover for directional consistency with the disc drive. An elevatorassembly of the feeder assembly lowers the top cover wireframe caddyuntil the first available top cover is disposed on a rotary actuatorassembly. With the top cover secured on the rotary actuator assembly,the linear positioning assembly positions the top cover in a coverpick-up position for pick-up by the robotic assembly.

The robotic assembly has an X-Y-axis positioning assembly supportingZ-axis end effector assemblies, the positioning assembly transports theeffector assemblies to predetermined positions. A first end effectorassembly picks and places the top cover adjacent the basedeck, thesecond end effector assembly grips and secures the top cover onto thebasedeck via the top cover fasteners.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top, partially cutaway view of a disc drive having a topcover assembled by a top cover installation station constructed inaccordance with the present invention.

FIG. 2 is a perspective view of the top cover installation station forinstalling the top cover on the disc drive of FIG. 1.

FIG. 3 is an exploded, partial cutaway, perspective view of the feederassembly of the top cover installation station of FIG. 2.

FIG. 4 is an exploded, perspective view of the robotic assembly of thetop cover installation station of FIG. 2.

FIG. 5 is an exploded perspective view of a first independentlyoperating Z-axis end effector assembly of FIG. 4.

FIG. 6 is an exploded perspective view of a second independentlyoperating Z-axis end effector assembly of FIG. 4.

FIG. 7 is a perspective view of a pair of independently operating Z-axisend effector assemblies formed by combining the first independentlyoperating Z-axis end effector assembly of FIG. 4 with the secondindependently operating Z-axis end effector assembly of FIG. 4.

DETAILED DESCRIPTION

Referring to the drawings in general, and more particularly to FIG. 1,shown therein is a top view of a disc drive 100 constructed inaccordance with the present invention. The disc drive 100 includes abasedeck 102 that has several fastener receptacles 103, the basedeck 102supporting various disc drive components, and a top cover 104 (shown inpart), with several mounting apertures 113, secured to the basedeck 102by top cover fasteners 105. The installed top cover 104 together withthe basedeck 102 provides a sealed internal environment for the discdrive 100. Numerous details of construction of the disc drive 100 arenot included in the following description as such are well known tothose skilled in the art and are believed to be unnecessary for thepurpose of describing the present invention.

Mounted to the basedeck 102 is a spindle motor 106 that has a top coverattachment aperture 107, the spindle motor supports several discs 108mounted on a spindle motor hub 109 that are secured by a clampring 110for rotation at a constant high speed. In addition to providing supportfor the stacked discs 108, the spindle motor hub 109 also provides atiming mark 111 used during the assembly process to reference theangular location of a source of rotational imbalance. Adjacent the discs108 is an actuator assembly 112 (also referred to as an “E-block”)which, pivots about a cartridge bearing 114 in a rotary fashion. Theactuator assembly 112 includes actuator arms 116 (only one shown) thatsupport load arms 118. Each load arm 118 in turn supports read/writeheads 120, with each of the read/write heads 120 corresponding to asurface of one of the discs 108. As mentioned, each of the discs 108 hasa data recording surface divided into concentric circular data tracks,and the read/write heads 120 are positionably located over data tracksto read data from, or write data to, the tracks.

The actuator assembly 112 is controllably positioned by a voice coilmotor assembly (VCM) 122, comprising an actuator coil 124 immersed inthe magnetic field generated by a magnet assembly 126. A latch assembly128 latches the actuator assembly in a predetermined park position whenthe disc drive 100 is turned off. A magnetically permeable flux path isprovided by a steel plate 130 (also called a pole piece) is mountedabove the actuator coil 124 to complete the magnetic circuit of the VCM122.

When controlled DC current is passed through the actuator coil 124, anelectromagnetic field is set up which, interacts with the magneticcircuit of the VCM 122 to cause the actuator coil 124 to move relativeto the magnet assembly 126 in accordance with the well-known Lorentzrelationship. As the actuator coil 124 moves, the actuator assembly 112pivots about the cartridge bearing assembly 114, causing the heads 120to move over the surfaces of the discs 108 thereby allowing the heads120 to interact with the data tracks of the discs 108.

To provide the requisite electrical conduction paths between the heads120 and disc drive read/write circuitry (not shown), read/write headwires (not separately shown) are routed on the actuator assembly 112from the heads 120 along the load arms 118 and the actuator arms 116 toa flex circuit 132. The read/write head wires are secured tocorresponding pads of a flex circuit printed circuit board (PCB) 134 ofthe flex circuit 132. The flex circuit 132 is connected to a flexcircuit bracket 136 in a conventional manner, which in turn is connectedthrough the basedeck 102 to a disc drive PCB (not shown) mounted to theunderside of the basedeck 102. The disc drive PCB provides the discdrive read/write circuitry which, controls the operation of the heads120, as well as other interface and control circuitry for the disc drive100.

To maintain the sealed internal environment for the disc drive 100, aseal gasket 138 is molded on to the top cover 104. Top cover 104 has aplurality of gasket attachment apertures 140 through which gasketmaterial flows during the gasket molding process. A continuum ofsymmetrically formed gasket material is disposed on both the top andbottom surfaces of the top cover 104 and injected through the apertures140. During the cure process, the gasket material injected into thegasket attachment apertures 140 bonds the portion of the seal gasketadjacent the top surface of the top cover to the portion of the sealgasket adjacent the bottom portion of the top cover 104, thereby sealingthe gasket attachment apertures 140 and forming the seal gasket 138. Agasket material found to be useful for this application is “Fluorel” bythe 3M company, and more specifically, 3M “Fluorel”, FE-5621Q.

FIG. 2 shows a top cover installation station 142 that installs the topcover 104 of the disc drive 100 on the basedeck 102 by securing the topcover fasteners 105 through mounting apertures 113 of the top cover 104into the fastener receptacles 103 of the basedeck 102, and into the topcover attachment aperture 107 of the spindle motor 106. A frame 144supports two primary assemblies, a feeder assembly 146 and a roboticassembly 148. The feeder assembly 146 prepositions the top cover 104 forpick-up by the robotic assembly 148, prior to the robotic assembly 148picking and placing the top cover 104 on the basedeck 102. A pair ofeffector assemblies 150, supported by the frame 144, cooperateindependently to position the top cover 104 into the basedeck 102 andsecure the top cover fasteners 105 on the basedeck 102. The first of thepair of end effector assemblies 150 is a top cover Z-axis end effectorassembly 152 that grasps then positions the top cover 104 on thebasedeck 102. The second of the pair of end effector assemblies 150 is afastener driving Z-axis in effector assembly 154 grips and removes thetop cover fasteners 105 from a fastener pick-up position 155 of afastener feeder assembly 156 and secures the top cover fasteners 105into the basedeck 102 to secure the top cover 104 on the basedeck 102 toform the disc drive 100.

Docking bracket 157 joins the feeder assembly 146 to the roboticassembly 148 for installation of the top cover installation station 142into an automated disc drive assembly line (not shown). By positioning aconveyor (not shown) through the robotic assembly 148 and then rollingthe feeder assembly 146, with the docking bracket 157, into position therobotic assembly 148 joins the feeder assembly 148 to form the top coverinstallation 142. For maintenance operations the docking bracket 157separates the feeder assembly 146 from the robotic assembly 148.

In operation, the robotic assembly 148 interacts with the feederassembly 142 to pick and place the top cover 104 on the basedeck 102then secures the top cover fasteners 105 into the fastener receptacles103 of the basedeck 102 and the top cover attachment aperture 107 of thespindle motor 106. To accomplish the operational steps of the top coverinstallation station 142, the top cover Z-axis end effector 152 graspsand aligns the top cover 104. At the same time, the fastener drivingZ-axis end effector assembly 154 grips, positions, and secures each topcover fastener 105 through the mounting apertures 113 of the top cover104. Some of the top cover fasteners 105 fit into fastener receptacles103 of the base deck. Some of the top cover fasteners 105 fit into thetop cover attachment aperture 107 in the spindle motor. All of the topcover fasteners operate to secure the top cover 104 to the basedeck 102and to the spindle motor 106 to form the disc drive 100.

FIG. 3 shows the frame 144 supporting a mounting plate 157 of the feederassembly 146 of FIG. 2, which supports an elevator assembly 158. Theelevator assembly 158 positions the top cover 104 for pick up by anescapement assembly 160. The escapement assembly 160 is supported by theelevator assembly 158 and includes a linear positioning assembly 162 anda rotary action 164. The rotary actuator assembly has several locatingpins 166 (one shown) that cooperate with the mounting apertures 113 ofthe top cover 104. The locating pins 166 register a position of the topcover 104 relative to the rotary actuator 164. In operation, the linearpositioning assembly 162 shuttles the rotary actuator assembly 164 intoa first position 167 for receiving the top cover 104 and then into acover pick-up position 168 (shown in outline form) for delivering thetop cover 104 for pick-up by the robotic assembly 148 of FIG. 2.

The mounting plate 157 supports a dial assembly 169 that supportsseveral top cover wireframe caddies 170. Each top cover wireframe caddy170 carries several top covers 104 for installation on the basedeck 102.The dial assembly 169 indexes the top cover caddy 170 into alignmentwith the elevator 158 to dispense the top covers 104 from the top covercaddy 170. The linear positioning assembly 162 shuttles the rotaryactuator 164 into alignment with the top cover beneath the wireframecaddy 170 to position the rotary actuator 164 for receipt of the topcover 104. The elevator assembly 158 lowers top cover wireframe caddy170 until the mounting apertures 113 of the top cover 104 are disposedon the locating pins 166. The linear positioning assembly 162 extractsthe top cover 104 from the top cover caddy 170 and rotates the top cover104 to be directionally consistent with the basedeck 102. After rotatingthe top cover 104, the rotary actuator 164 positions the top cover 104in the cover pick-up position 168 for pick-up by the robotic assembly148. Additionally, the frame 144 further supports a station computer 171that manages the operations of the automated top cover installationstation 142.

FIG. 4 shows the frame 144 cooperating with the support plate 172 thatsupports an X-Y-axis positioning assembly 173. The X-Y-axis positioningassembly 173 supports the pair of end effector assemblies 150 andprovides the X-Y-axis positioning requirements for the top coverinstallation station 142. Four attachment fasteners 174 (one shown)secure the pair of end effector assemblies 150 to the X-Y-axispositioning assembly 173 by engaging the threaded attachment apertures176. A lift and locate assembly 175 secures the basedeck 102 within thetop cover installation station 142 during the top cover 104 installationprocess.

In operation, the X-Y-axis positioning assembly 173 positions the pairof end effector assemblies 150 to pick up top cover fasteners 105 fromthe fastener pick-up position 155 of the fastener feeder assembly 156.When positioned, the fastener driving Z-axis end effector assembly 154travels downward in the Z direction to engage the top cover fastener105, grips the top cover fastener 105 and returns to a home position.With the top cover fasteners 105 gripped by the fastener driving Z-axisend effector assembly 154, the X-Y-axis positioning assembly 173transports the pair of end effector assemblies 150 into alignment withthe top cover 104 disposed on the rotary actuator 164 of the escapementassembly 160 of FIG. 3 and positioned in the cover pick-up position 168.When aligned, the top cover Z-axis end effector assembly 152 travelsdownward in the Z direction to engage the top cover 104, then grasps thetop cover 104 and returns to a home position. With the top cover 104grasped by the top cover Z-axis end effector assembly 152, the X-Y-axispositioning assembly 173 transports the pair of end effector assemblies150 into alignment with the basedeck 102. When positioned, the top coverZ-axis end effector 152 travels downward in the Z direction to place andhold the top cover 104 adjacent the basedeck 102.

FIG. 5 shows the top cover Z-axis end effector assembly 152 of FIG. 4. Abaseplate 178 supports a linear slide assembly 180, the linear slideassembly 180 permits travel in the Z direction for the end effectorassembly 152. The linear slide assembly 180 supports a left plate 182that has a lift bracket 184 and a pick-up plate 186 with suction cups188 and end effector standoffs 189. The left plate 182 registers thepick-up plate 186 adjacent the top cover 104 and, under vacuum, thesuction cups 188 grasp the top cover 104. Additionally, the baseplate178 supports a cylinder mount 190 that supports a first air cylinder 192that has a positioning rod 194. The first air cylinder 192 provides aninstrumentality for vertical travel in the Z direction of the top coverZ-axis end effector assembly 152. The cylinder mount 190 maintains thebody of the first air cylinder 192 stationary in relation to thebaseplate 178. A first jam nut 196 attaches the positioning rod 194 tothe lift bracket 184. The positioning rod 194 travels in the Zdirection, under air pressure, in response to the control computer 171to either lower or raise the pick-up plate 186. The suction cups 188 areprotected by end effector standoffs 189 (one shown) against beingoverdriven by the first air cylinder 192. The end effector standoffs 189also serve to constrain the top cover 104 against the basedeck 102during the attachment of the top cover fasteners 105 to the basedeck 102and the spindle motor 106.

An end effector support gusset 198 provides structural support betweenthe pick-up plate 186 and the lift plate 182 to assure consistent andrepeatable performance by the top cover Z-axis end effector assembly 152during operation of the top cover installation station 142. Thebaseplate 178 also supports a mounting plate 200 that provides mountingports 201 for the attachment fasteners 174 to pass when securing the topcover Z-axis end effector assembly 152 to the X-Y-axis positioningassembly 173. And finally the baseplate 178 supports a top cover plate202, a rear cover plate 204 and a front cover plate 206. Collectively,the top cover plate 202, the rear cover plate 204 in the front coverplate 206, in conjunction with the pick-up plate 186, provide aconfinement chamber and an exodus path for particulate generated by thetop cover Z-axis end effector assembly 152 during the operation of thetop cover installation station 142.

FIG. 6 shows the fastener driving Z-axis end effector assembly 154 ofFIG. 4. The attachment fasteners 174 of FIG. 5 secure the fastenerdriving Z-axis end effector assembly 154 to be X-Y-axis positioningassembly 173 by passing through mounting holes 208 provided by adovetail adapter plate 210. To secure the pair of end effectorassemblies 150 to the X-Y-axis positioning assembly 173, the attachmentfasteners 174 of FIG. 5 sequentially pass through the mounting holes 208of the fastener driving Z-axis end effector assembly 154, then throughthe mounting ports 212 of the top cover Z-axis end effector assembly 152prior to engaging the threaded attachment apertures 176 of the X-Y-axispositioning assembly 173 of FIG. 4. The dovetail adapter 210 cooperateswith a Z-axis positioning plate 212 to facilitate motion in the Zdirection for the fastener driving Z-axis end effector assembly 154. TheZ-axis positioning plate 212 supports a linear bearing 214 that has ascrewdriver mounting block 216 supporting a screwdriver attachmentassembly 218 with power screwdriver 220. The linear bearing 214 assuresfreedom of travel of the fastener driving Z-axis end effector assembly154 during the operation of the top cover installation station 142. Inaddition to supporting a screwdriver attachment assembly 218, thescrewdriver mounting block 216 rides on a linear bearing 214 to maintainstability in orientation between the attachment assembly 218 and theZ-axis positioning plate 212. The screwdriver attachment assembly 218constrains the power screwdriver 220 and prevents shifts in theorientation of power screwdriver 220 during the operation of the topcover installation station 142.

In operation, the power screwdriver 220 grips and then secures the topcover fasteners 105 by first passing the top cover fastener 105 throughthe mounting apertures 113 of the top cover 104, then into the top coverattachment aperture 107 of the spindle motor 106 and into the fastenerreceptacles 103 of the basedeck 102 of FIG. 1. The linear bearing 214also supports an air cylinder mounting block 222 with an air cylinderamount 224 supporting is a second air cylinder 226 that has apositioning shaft 228. The positioning shaft 228 is secured to thescrewdriver attachment assembly 218 by a second jam nut 230, thepositioning shaft 228 operates under air pressure applied to the secondair cylinder 226 by raising or lowering the power screwdriver 220 whenactivated by the station computer 171. The air cylinder mounting block222 remains stationery relative to the linear bearing 214 to capture thebody of the second air cylinder 226, allowing the positioning shaft 228to operate freely. An exhaust port assembly 232 and a cover 234co-operate to remove particulate generated by the fastener drivingZ-axis end effector assembly 154 during the operation of the top coverinstallation station 142.

FIG. 7 shows the pair of end effector assemblies 150 with the top coverZ-axis end effector assembly 152 aligned with the fastener drivingZ-axis end effector assembly 154 for cooperating independent functioningneeded by the top cover installation station 142 to install the topcover 104 with the top cover fasteners 105 onto the basedeck 102 to formthe disc drive 100 of FIG. 1. Exhaust ports 236 operate under a vacuumpressure to expel particulate generated by the pair of end effectorassemblies 150 during operation of the automated disc drive assembly142. The vacuum pressure also enables suction cups 188 to grasp the topcover 104 and the powered screwdriver 220 to grip the top coverfasteners 105. A screwdriver access port 238, provided by the pick-upplate 186, accommodates unencumbered Z-axis travel by the powerscrewdriver 220 during active operation of the fastener driving Z-axisend effector assembly 154 and further accommodates the independentZ-axis travel of both the fastener driving Z-axis end effector assembly154 and the top cover Z-axis end effector assembly 152.

The present invention provides a top cover installation station (such as142) with a feeder assembly (such as 146) and a robotic assembly (suchas 148) for installing a top cover (such as 104) with top coverfasteners (such as 105) on a basedeck (such as 102) of a disc drive(such as 100). The feeder assembly supports top cover wireframe caddies(such as 170), each caddy containing top covers. A dial assembly (suchas 169) transports each caddy into alignment with an elevator assembly(such as 158) that aligns the top cover with an escapement assembly(such as 160) that removes the top cover from the caddy. The roboticassembly has an X-Y-axis positioning assembly (such as 173) supporting apair of Z-axis end effector assemblies (such as 150), the positioningassembly transporting the pair of effector assemblies to predeterminepoints. A first end effector assembly (such as 152) picks and places thetop cover adjacent the basedeck and a second end effector assembly (suchas 154) grips and secures each top cover fastener through each mountingaperture (such as 113) and into each fastener receptacle (such as 103)of the basedeck.

It is clear that the present invention is well adapted to attain theends and advantages mentioned as well as those inherent therein. While apresently preferred embodiment of the invention has been described forpurposes of the disclosure, it will be understood that numerous changescan be made which will readily suggest themselves to those skilled inthe art. Such changes are encompassed within the spirit of the inventiondisclosed and as defined in the appended claims.

What is claimed is:
 1. A method for installing a top cover and top coverfasteners onto a basedeck of a disc drive by the steps comprising: (a)providing the basedeck to a top cover installation station; (b)presenting each top cover fastener to a fastener pick-up position via atop cover fastener feeder assembly; (c) advancing the top cover to acover pick-up position via a cover feeder assembly; (d) gripping thefastener from the fastener pick-up position via a second end effectorassembly; (e) grasping the top cover from the cover pick-up position andpositioning the top cover adjacent the basedeck via a first end effectorassembly; (f) aligning the top cover adjacent the basedeck andmaintaining alignment via the first end effector assembly whileinstalling the top cover fastener with the second end effector assembly;and (g) securing the top cover fasteners through the mounting aperturesinto the top cover attachment aperture and the fastener receptacles viathe second end effector assembly.
 2. The method of claim 1 wherein theadvancing step (c) further comprises: (c1) indexing a wireframe topcover caddy carrying a plurality of top covers via a dial assembly intoalignment with an elevator assembly dispensing the top cover from thewireframe top cover caddy; (c2) shuttling a rotary actuator having alocating pin into alignment with the top cover via a linear positioningassembly, wherein the locating pin registers the top cover to the rotaryactuator; (c3) lowering the wireframe top cover caddy via the elevatorassembly to dispose the mounting apertures on the locating pin; (c4)extracting the top cover from the wireframe top cover caddy via thelinear positioning assembly; and (c5) rotating the top cover via therotary actuator into orientation with the basedeck.
 3. The method ofclaim 1 wherein the gripping step (d) further comprises: (d1) aligningthe second end effector assembly adjacent the fastener pickup positionwith a robotic assembly; (d2) positioning a power screwdriver adjacentthe top cover fastener with a second air cylinder; (d3) activating avacuum port to secure the top cover fastener within the powerscrewdriver; and (d4) retracting the second end effector assembly fromthe fastener pick-up position.
 4. The method of claim 1 wherein thegrasping step (e) further comprises: (e1) aligning the first endeffector adjacent the cover pick-up position with a robotic assembly;(e2) positioning a pick-up plate with suction cups adjacent the topcover with a first air cylinder; (e3) activating the suction cups with avacuum port securing the top cover to the first end effector; and (e4)retracting the first end effector assembly from the cover pick-upposition.
 5. The method of claim 1 wherein the basedeck, which has aplurality of fastener receptacles, supports a disc pack having a topcover attachment aperture, the top cover providing mounting aperturesaligned with the fastener receptacles, and wherein the aligning step (f)further comprises: (f1) positioning the top cover and the top coverfastener secured by a pair of end effector assemblies adjacent thebasedeck with a robotic assembly; (f2) aligning the mounting aperturesadjacent the fastener receptacles and the top cover fastener adjacentthe top cover attachment aperture; and (f3) pressing the top cover intomating contact with the basedeck maintaining alignment of the mountingapertures with the fastener receptacles while installing the top coverfasteners.
 6. The method of claim 5 wherein the securing step (g)further comprises: (g1) driving the top cover fastener through themounting aperture and into the attachment aperture with a powerscrewdriver; (g2) torqueing the top cover fastener to a predeterminedlevel; (g3) retracting the pair of end effector assemblies from contactwith the top cover; (g4) aligning the second end effector assemblyadjacent the fastener pick-up position with the robotic assembly; (g5)positioning the power screwdriver adjacent the top cover fastener with asecond air cylinder; (g6) activating a vacuum port to secure the nexttop cover fastener within the power screwdriver; (g7) retracting thesecond end effector assembly from the fastener pick-up position; (g8)positioning the top cover fastener secured by the power screwdriverthrough a predetermined one of the mounting apertures and into contactwith the corresponding aligned fastener receptacle; (g9) driving thenext top cover fastener through the mounting aperture and into thefastener receptacle; (g10) torqueing the next top cover fastener to apredetermined level; (g11) retracting the pair of end effectorassemblies from contact with the top cover; (g12) repeating method steps(g4) through (g11) for each remaining fastener receptacle; and (g13)releasing the basedeck from a lift and locate assembly.